It is expected that an exhaustion problem of valuable metal mineral resources, which has recently been an issue, will hinder development of human civilization in the near future.
An amount of lithium mined from the earth in consideration of economical feasibility of a lithium mineral resource is only about 4.1 million tons in the world, and a lithium resource is a rare resource expected to be depleted within the next decade.
The lithium resource as described above is concentrated in some nations, and it is actually impossible to apply a method of mining lithium from ore and salt lake in Korea, or the like, in which a lithium reserves is significantly small.
However, even though among resources dissolved in sea water, lithium is present at a trace amount of 0.17 mg/l, since a total amount of dissolved lithium is 230 billion tons, it is known that a large amount of lithium is present in sea water.
Therefore, a mineral recovery technology capable of selectively extracting a specific valuable metal ion melted (dissolved) in sea water may sufficiently serve as a growth engine of the national economy by reducing the dependency on overseas resources and enabling a stable supply of resources, and is a significantly important technology for continuous national economical development for the future.
In most of the related arts associated with the technology of recovering a valuable metal from sea water, the development focused on ion exchange and adsorption technologies of an inorganic or organic material for selectively removing a specific metal ion has been conducted.
Particularly, in general, lithium is recovered by a technology of performing acid treatment after embedding inorganic compound particles such as a manganese oxide as a lithium ion molecular sieve in a polymer such as polyvinyl chloride (PVC) or putting the inorganic compound particles in a storage made of a polymer membrane to selectively exchange ions.
The technologies according to the related art have an advantage in that a recovery rate of the lithium ion from sea water is high.
However, since it takes a significantly long time to adsorb the specific ion, economical feasibility and efficiency are low, and since a toxic material such as an acid should be used in a post-treatment process for recovering the ion such as an ion separation process, there are problems such as corrosion of a system, environmental contamination, and the like.
In order to solve these problems, the present inventors filed Korean Patent No. 10-1136816.
In this technology, an electrode module on which metal ions such as a lithium ion, and the like, are adsorbed is provided, and a solution in which metal ions are present is moved to the electrode module by a pump, such that the lithium ions are attached to the electrode module to which a negative polarity is applied.
In addition, at the time of separating the attached lithium ions, the lithium ions are separated from the electrode module by changing a polarity of the electrode, such that lithium contained in a solution such as sea water, or the like, may be recovered.
However, in the related art as described above, there is a limitation in implementing a large size, and energy efficiency and economical feasibility are beyond expectations.